Based on the original 1940s Gotham Hobby DEEZIL, the CS version is a good running model engine, unlike most originals which very few were capable of running due to poor design changes and poor tolerancing. My CS DEEZIL .125 cubic inch engine is turning a 10-6 master airscrew prop using my test fuel of ~ 33 percent harley 60 wt motor oil , remainder ether... As the engine warmed up, the compression needed reduced.... earlier, the prop clipped my blue glove but missed my fingers somehow.... Phew....